More than any one architect or public servant, Ms. Huxtable served as a catalyst for New York City’s recent architectural rebirth, from the uninspired days of the 1960s when white wedding-cake apartment buildings and demolished landmarks like Penn Station were the norm, to the current era, when breathtaking skyscrapers, a waterfront revitalization and new historical districts are sprouting, even in Brooklyn, whose comeback was once unthinkable.